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rgba_trans_p: any non-zero alpha must be displayed #1540

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nick black 2021-04-16 01:03:32 -04:00
parent e1d97bfb62
commit 4442a9fea9
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1 changed files with 7 additions and 4 deletions
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11
src/lib/internal.h
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@ -1472,12 +1472,15 @@ int drop_signals(void* nc);
void ncvisual_printbanner(const notcurses* nc);
// alpha comes to us 0--255, but we have only 3 alpha values to map them to.
// settled on experimentally. if transcolor is non-zero, match its lower 24
// bits against the color, and treat a match as transparent.
// alpha comes to us 0--255, but we have only 3 alpha values to map them to
// (opaque, blended, and transparent). it's necessary that we display
// something for any non-zero alpha (see #1540), so the threshold is 1.
// we might want to map this to blended, but we only use opaque and
// transparent for now. if |transcolor| is non-zero, match its lower 24
// bits against each pixel's RGB value, and treat a match as transparent.
static inline bool
rgba_trans_p(uint32_t p, uint32_t transcolor){
if(ncpixel_a(p) < 192){
if(ncpixel_a(p) == 0){
return true;
}
if(transcolor &&